Cooling apparatuses of an internal combustion engine mounted on a vehicle include a cooling device configured to control a coolant passage by using an electrically controlled control valve which is arranged instead of a thermostat in the coolant passage for a flow of a coolant (cooling water), so that fuel efficiency is improved by acceleration of coolant temperature rise.
Coolant temperature control using the control valve is performed in the following manner. Specifically, when the internal combustion engine is in a cold state, a coolant temperature is raised to a high temperature (110° C., for example) as quickly as possible. When the coolant temperature reaches the high temperature, the control valve is immediately controlled so that the temperature of the coolant is at a slightly lower temperature (90° C., for example) to avoid knocking.
Meanwhile, conventional cooling apparatuses include a cooling device having a minimum circulation path in addition to the coolant passage. When the internal combustion engine is started to be warmed up, all the control valves (selector valves) are closed to cause the coolant to flow through the minimum circulation path. Thereby, the internal combustion engine is warmed up quickly.
In a control device of a cooling system according to JP 2011-220156 A (“Patent Document 1”), a radiator configured to cool a coolant (cooling water) in an internal combustion engine, a heat exchanger for air conditioning, and an accessory of the internal combustion engine (a throttle body) are provided with coolant passages, respectively, and are connected to the internal combustion engine. These coolant passages are provided with control valves (selector valves), which are opened sequentially according to the coolant temperature. Specifically, when the coolant temperature reaches a predetermined set temperature, it is determined that the internal combustion engine is in the warmed-up state. The coolant passage for the radiator, the coolant passage for the heat exchanger for air conditioning, and the coolant passage for the accessory of the internal combustion engine are opened in this order.